Whether you think it’s a staple or just plain sloppy, its staying power is undeniable. But if you haven’t yet bought your cream of mushroom soup and French-fried onions, you may be hard pressed to find them today. And since you make it but once a year, we’re willing to bet you don’t have a stockpile of green-bean-casserole components in your pantry. So would you believe that green-bean casserole was first created because it could be made with ingredients almost everyone already had?

Indeed, green-bean casserole was drawn up in the Campbell’s Kitchen in 1955. The “aha” moment is credited to home economist Dorcas Reilly, who was tasked with combining as few ingredients as possible to create a nutritious dinner. She’s also the driving force behind tomato-soup meatloaf – that doesn’t seem to have taken off quite as well. Nor was green-bean casserole an instant hit; there were three previous versions of the recipe that didn’t quite fly. But a bit of tweaking, and it took off. It wasn’t created exclusively as a Turkey Day dish, but when it appeared in an Associated Press feature for Thanksgiving 1955, its associations were implied.

Green-bean casserole has found its place among the Turkey Day trimmings ever since. If you haven’t noticed, Thanksgiving is a holiday dominated quite heavily by orange and yellow veggies. It’s that magical combination of green beans and cream of mushroom soup and topped with French-fried onions that adds a much needed infusion of green on your plate. And Campbell’s seems O.K. with that. Thirty million green-bean casseroles will appear on Thanksgiving tables tomorrow, according to John Faulkner, director of brand communications for Campbell’s. But there’s always room for one more.

“We’re in reminder mode right now,” Faulkner says. The dish is appearing in the company’s commercials to ensure we don’t forget about it. After all, the ingredients are simplistic enough, Faulkner notes, that you can make it Thanksgiving Day and “you probably have a high confidence level that you’re not going to screw it up. Especially if you’re new to the family.”

And their reminders appear to be working. In 2005, Campbell’s estimated it sold $20 million worth of cream of mushroom soup just to people making green-bean casserole for today’s dinner. Faulkner notes that cream of mushroom today is still Campbell’s third most popular soup – right behind chicken noodle and tomato – despite our inability to recall a single other dish that calls for the soup.

So how is the company getting us to cast aside green-bean casserole’s Thanksgiving Day bias? It’s offering recipe tweaks to spice it up or switch it up. “For extra crunch we recommend you add water chestnuts, add shredded cheddar or red peppers for color,” Faulkner says. Among his most radical suggestions: ditch the green beans in favor of broccoli. Whoa. So we’re not ready to make such an extreme shift in this classic dish. But we are ready to cook – and hopefully, so are you. Here’s Campbell’s original recipe: